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I am building a lab power supply that is going deliver 0-6 A at 0-35 V, maybe 40 V. The power supply is almost ready to go in use.

On the power supply there are nice big banana connectors that can handle easily 10 A.

To wire circuits and other devices I need a cable with banana connectors. I started thinking if I am able to make it myself.

So here is my idea:

I order nice banana male plugs and a nice thick black and red silicon cable.

My problem is: which size do I need for around 6 A? I have looked at wire current tables, they suggest a cable size of 13AWG for 7.4 amps power transmission, but the same cable can handle 35 A for chassis wiring.

They explain that chassis wiring are lose runs of cables surrounded by air. Another calculator says I only need 18AWG.

Can somebody help me with a suggestion on which cables in need to buy. To clarify the specs that the cable needs to handle are:

  • 0-40 V
  • 0-6 A
  • 80 cm in length
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  • \$\begingroup\$ One easy way to solve this conundrum is to look at the manufacturer's specifications for the particular cable, which should be also provided by any reputable seller of it. \$\endgroup\$ – Ian Bland Jul 22 '17 at 15:42
  • \$\begingroup\$ What is your spec for ripple and DC drop? Do you want to do remote V sensing? What load ? and Load regulation error? WHy reinvent the wheel without considering all the issues? \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jul 22 '17 at 16:32
  • \$\begingroup\$ do U know Ohm's law for cables? or how to calc inductance? or doesn't matter? \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jul 22 '17 at 16:42
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I made up some PSU leads with silicone wire and nice banana plugs.

I sourced some 16 AWG silicone-insulated wire from eBay, and the banana plugs and croc clips from CPC. The silicone is not as nice as, say, the stuff on Fluke test leads, but it is good enough - the important point is the large number of wire strands which means the wire is flexible.

Important point: I found that the wire only just fits through the insulation boots on the banana plugs, so that is something to take in to consideration. Also, I crimped ferrules on the wire ends and that made them only just fit into the holes on the banana plugs.

Refs:

What is the “Max current” for AWG#16?

Fancy croc clips: Multi Contact 20285-1. (Someone seems to have been quite enthusiastic in their review.)

Banana plugs with only a 2.5 mm hole for the wire: Multicomp A-1.126-R.

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  • \$\begingroup\$ Thanks for answering my question. I decided to order 1 meter of red and black 12awg wire from ebay. I also ordered 2 Nakamichi banana plugs, They seem to be of reasonably high quality. What i will put on the ends of the cable i haven't decided yet. \$\endgroup\$ – Lux Jul 25 '17 at 9:25
  • \$\begingroup\$ If you put banana plugs on the other end, you can get croc clips (like the ones I linked to), spade connectors, and so on which plug onto them. That way you have a choice of connectors. \$\endgroup\$ – Andrew Morton Jul 25 '17 at 9:30
  • \$\begingroup\$ That was the same idea i had in mind this morning. Thanks for the link. i will order them \$\endgroup\$ – Lux Jul 26 '17 at 10:30
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So, generally, I'd advise to analyze the voltage drop, resulting power converted to heat, the resulting temperature raise etc., but honestly:

6 A is below what common household power cables are designed to carry. AWG 18 has 1mm in diameter – not really much.

I'd simply oversize a bit and take a > 2.5 mm² cross-section cable. They come cheap, are used all over the place in e.g. automotive control and can easily be bought speced to have more than sufficient isolation.

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  • \$\begingroup\$ Thanks for answering my question. you are right about the 2,5mm cable but one problem most of them are solid copper. other are stranded but not that flexible. \$\endgroup\$ – Lux Jul 25 '17 at 9:19

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